The field of the subject of this disclosure is that of equipment. More specifically, the disclosure relates to production machinery, and in particular equipment provided for screwing with a predetermined torque.
In the field of the subject of this disclosure, screwing tools are very commonly used in the industrial sector, whether the tools are stationary (including tools mounted on machines or manipulators) or portable.
These tools can include electric motor or pneumatic means according to the envisaged applications.
According to a common implementation of these tools, they are connected by suitable connectors to an electronic controller (in the form of an electrical box) making it possible to program a large number of operation cycles (for example 250 cycles), wherein each cycle can be composed of 20 operation phases.
These cycles can be programmed directly by a keyboard comprised by the electric box or by associated programming software (the box(es) then being connected to the programming system by a ground network, Ethernet or other type of network).
These systems make it possible to ensure the traceability of the operations performed by the tool, by, for example, recording results such as the final screwing torque, the screwing speed, the final screwing angle, the date and time of the operations, or the curves representing the quality (Good or Poor, according to predetermined parameters) of the screwing performed.
The tool itself can also comprise means for indicating the screwing quality, for example by providing a report “Good/Poor” that can be displayed by LEDs.
It is understood that systems of this type make it possible to perform a wide range of parameterisation and control operations.
Nevertheless, as mentioned above, equipment assemblies such as those described above require the use of connection networks that are more or less logical in order to connect the controllers to the tools and the controllers to the programming equipment.
It is understood that these constraints can result in an increase in the operating cost.
According to a known technique, the tool is connected to the electrical section so as to supply power to control electronics integrated in the tool. In this case, the tool has a small display device and some control buttons.
It is understood that, in one or the other of the technologies described above, the data concerning the screwing torque is essential for properly controlling the tools and in order to be capable of obtaining a follow-up on the screwing results.
Indeed, the data on the screwing torque is used numerous times, to of course ensure the quality of the assembly to be produced by screwing, but also to allow for traceability of the operations and to carry out statistical processing of the tightening data.
In addition, the tools are controlled by command means, integrated in the tool or external to the tool, which define the parameters of operation of the tool according to the assembly to be performed.
However, whether it is for the control and/or the follow-up on the screwing parameters or for the proper execution of these parameters, it is necessary to ensure, above all, the good condition of operation of the tools.
In other words, the reliability of the tools must be capable of being verified, regularly during the entire period of use of the tools, so as to be capable of performing maintenance operations, preferably preventative maintenance. It is thus desirable to avoid in particular the conditions of wear leading to the breakage of the tools on the production line, requiring this line to be stopped so that the tool can be replaced. This of course adversely affects the overall efficiency of the production line concerned.
Currently, preventative maintenance is limited to recommendations by the tool manufacturers, which recommendations involve a servicing schedule.
Optionally, a system of calculations performed by a software program contained in a tool control box automatically determines the servicing schedule according to the real conditions of use of the tool (torque, speed, temperature, etc.).
It is understood that in one case or another, the servicing recommendations result from an empirical approach leading to only an estimation of the wear of the tool.
Such an approach to the servicing and/or maintenance of tools can therefore lead to two types of situations:                the recommendations are prudent and encourage servicing or maintenance that is more frequent than necessary: this tends to increase the tool operation cost;        certain tools deteriorate between two servicing operations, possibly to the point of causing a permanent defect in the tools concerned, possibly resulting in breakage of the tools during use; this can also cause defective work on the assemblies produced by a defective tool before its state is detected; in any case, this type of situation is unacceptable in that it can lead in particular to notable operating losses.        
The subject of this disclosure relates to a screwing tool including at least one rotary member mounted in a tool body and capable of producing at least one vibration frequency representing a condition of wear of said rotary member(s), characterised in that it includes means for measuring said vibration frequency or frequencies intended to communicate with means for processing said measurement, making it possible to compare it with at least one reference frequency so as to determine the condition of wear.
Thus, owing to the subject of this disclosure, it is possible to determine the real condition of wear of a tool, and more specifically of the rotary members that constitute it.
Indeed, each rotary member of the tool produces a characteristic frequency that can be calculated, which is a function of the rotation speed and the geometry of the member considered.
It is then possible for a new tool, and, for each of the characteristic frequencies, to perform a measurement and a recording of the amplitude. These amplitudes constitute reference amplitudes corresponding to a new condition of the tool.
During the lifetime of the tool, the mechanical members tend to become worn and their vibration amplitude increases. The measurement of the amplitude of the characteristic frequencies and their comparison with the reference amplitudes makes it possible to assess the degree of wear of the various members.
It is therefore understood that the subject of this disclosure makes it possible to optimise the servicing and/or maintenance interventions, which are activated and performed on the basis of a condition of wear that is measured and no longer only estimated.
It is therefore possible in this way to better anticipate situations of wear, and even the breakage of tools.
More generally, the subject of this disclosure makes it possible to obtain improvements in numerous control operations and/or in the assembly quality, by regularly ensuring the good condition of the tools and therefore their reliability.
According to an advantageous solution, said rotary member(s) are intended to produce a tightening torque, with said measurement means including at least means for measuring said torque.
Indeed, it is noted that the signal for measuring the torque includes all of the data representing the vibrations of the rotary member(s) of the tool.
In other words, the measurement of the tightening torque provides the data necessary for measuring the condition of wear, without it being necessary to add components to the tool body or to modify the existing components.
Said processing means advantageously include calculation means making it possible to process a frequency spectrum obtained on the basis of a signal transmitted by said means for measuring said torque.
Thus, the signal for measuring the torque can have a spectrum of which the lines can easily be compared to a reference frequency or to a series of reference frequencies.
Said processing means preferably include means for storing a reference frequency relative to each of said rotary members.
In this way, it is possible to issue a diagnosis of the condition of wear not only for the motor but also for the associated rotary members, each being characterised by a reference vibration frequency.
In this case, a reference frequency is preferably stored for at least one of the members belonging to the following group:                motor;        bell crank member; and        gear member.        
It is noted that if a bell crank member is implemented, the head of the tool integrates a conical torque and the ball rollers, which are sensitive mechanical members capable of producing a characteristic frequency of which the amplitude can be compared, as for the other rotating members, to reference amplitudes.
According to one embodiment, said processing means are integrated in a control unit separate from said tool.
It is thus possible to collect all of the data on the preventative maintenance on a unit independent of the tool, which unit can also perform other functions such as the control and/or the parameterisation of the tool.
It is noted that the dispatching and processing of preventative maintenance data on a control unit separate from the tool makes it possible to use the tools currently available, without any modification thereof.
However, it is possible in other embodiments that can be envisaged, to integrate the processing of the maintenance data directly in the tool, insofar as the dimensions thereof allow it.
Said unit advantageously includes at least one display device.
It is thus possible to display specific information, as text. However, the use of visual signals, such as lights and colours, can also be envisaged.
In one embodiment, said unit includes communication means capable of being connected to a communication network.
The control unit can thus send data to a remote unit, for centralising data, for example, by means in particular of the computer network of a company.
The subject of this disclosure also relates to a control unit intended to be provided in equipment including at least one rotary member mounted in a tool body and capable of producing at least one vibration frequency representing a condition of wear of said rotary member(s), characterised in that it includes means for processing at least one vibration frequency measurement making it possible to compare it with at least one reference frequency so as to determine said condition of wear, which equipment includes means for measuring said vibration frequency or frequencies.
The subject of this disclosure also relates to a method for checking the condition of wear of equipment including at least one rotary member mounted in a tool body and capable of producing at least one vibration frequency representing a condition of wear of said rotary member(s), characterised in that it includes the steps of:                measuring said vibration frequency or frequencies; and        comparing said vibration frequency or frequencies with at least one reference frequency in order to determine said condition of wear.        